Engine/Shaders/TdToneMapExposurePixelShader.usf

#include "Common.usf"


sampler2D SceneDownsampledTexture;
sampler2D PreviousExposureTexture;
float4 ExposureSettings; //Packed (Manual,MaxDeltaUp,LowClamp,HighClamp)
float MaxDeltaDown;


void Main(
	in float2 SceneTexCoord : TEXCOORD0,
	out float4 OutColor : COLOR0
	)
{
	half3 	tmp2 = tex2D(SceneDownsampledTexture,float2(0.5,0.5)).rgb;
	if ((!(tmp2.r > 0)) && (!(tmp2.r < 0))) // Nice NaN check for the nice optimizing compiler!
		tmp2 = float3(0.25,0.25,0.25);

	half	Luminosity = dot(tmp2,float3(0.3,0.59,0.11));

	half	TargetExposure = sqrt(0.25 / clamp(Luminosity,0.0000001,5000.0));
	TargetExposure = clamp(TargetExposure,ExposureSettings.b,ExposureSettings.a);
	half tmp = tex2D(PreviousExposureTexture,float2(0.5,0.5)).r*64;

	half	LastExposure = clamp(sqrt(tmp),ExposureSettings.b,ExposureSettings.a);

	float a = abs(TargetExposure - LastExposure);
	float sqr = (LastExposure + clamp((TargetExposure- LastExposure)*a,-MaxDeltaDown*a*a,ExposureSettings.g*a*a));

	sqr = sqr*sqr;

	OutColor = sqr*ExposureSettings.r/64;
}